Biomechanics

The study of forces and their effects on the human body

Sir Isaac Newton developed three basic laws that explain the relationship between motion and force

A push, a pull or a twist

Force = Mass x Acceleration

LAW OF INERTIA“A body continues in its state of rest or

uniform motion unless an unbalanced force acts upon it“

So what does this mean?A body will remain at rest or will continue

moving (in the same direction) until another force acts on it

Inertia is… a body’s tendency to remain at rest or in

motion. The more mass an object has, the larger its inertia is. Therefore is more reluctant to change its state of motion.

Who has more inertia in this image?

This soccer ball will remain at rest until a force acts on it…e.g. strong winds, or someone kicking it

LAW OF ACCELERATION ‘The acceleration of an object is directly

proportional to the force causing it, is in the same direction as the force, and is inversely proportional to the mass of the object’

This means… When a force is applied to an object it will move in

the direction the force was applied, and, depending on the size of the force and the size of the object, the object will accelerate accordingly

Class experiment…

A smaller object will move faster than a larger object.

A greater force will move an object faster than a smaller force

Force = Mass x acceleration

THE LAW OF REACTION ‘Whenever a force is applied there is an

equal and opposite reaction’

e.g. Jumping If a person exerts a force onto the ground in order to push off, theground will exert an equal and opposite force on the person, pushing them up

into the air Upward

Downward

HANDBALL EXAMPLE In your groups, choose ONE of Newton’s

LawsDescribe how you can use this law to your

advantage in Handball

Levers allow you to apply force and speed more easily.

Consist of 5 parts - Fulcrum (pivot point), Force, Force arm, Resistance and a Resistance Arm

FORCE ARM

Resistance

Fulcrum

FORCE

Resistance ARM

Allow force to be applied from Outside the body

e.g.

Are inside the human body. Most important Levers These levers are made up of a:

Joint = FulcrumBones = Lever armsMuscles = Force

Load = resistance Effort = force

Levers can be classed into 3 types:

1st Class 2nd Class 3rd Class – Most levers in human body are 3rd

class

In a 1st Class Lever, the Fulcrum sits between the load (resistance) and force applied (effort)

e.g. See-saw

In a 2nd Class Lever, the Load (resistance) sits between the fulcrum and the force applied.

e.g. Wheel Barrow

In a 3rd class lever, the force applied sits between the Fulcrum and the load (resistance)

Third class levers allow more speed to be produced because resistance arm is longer than force arm

e.g. Bicep curl

To Manipulate the Lever length the resistance arm needs to be altered (via bending or straightening the joint)

Longer levers result in greater speed at the end of the lever arms – this is beneficial for throwing and striking objects (e.g. throwing a handball).

Short levers result in fast and strong movements to occur– this is beneficial for moving body parts quickly and applying strength for pushing, pulling and lifting objects.

1. What class of lever are most of the limbs in human body?

2. Force = _______ x ________ 3. Newton’s 1st law is the law of _______ 4. Newton’s 2nd law of reaction means… ? 5. What type of joint is the elbow joint? And

what muscle causes elbow flexion

1. What class of lever are most of the limbs in human body? 3rd CLASS

2. Force = MASS x ACCELERATION 3. Newton’s 1st law is the law of INERTIA 4. Give an example of Newton’s 2nd law? BOUNCING A BALL, JUMPING 5. What type of joint is the elbow joint? And

what muscle causes elbow flexion HINGE JOINT, BICEP

‘the sum of all forces generated by each body part’

Force summation allows maximum force to be produced

For maximum force production:1. The force from all different body segments

needs to be added together2. Use large muscles then smaller muscles3. You need to sequence timing of body

segments4. The more body segments that are involved in

the movement, the more possible force that can be produced

Throwing example:

Time

Large Force

Small ForceShoulder/arm

Shoulder/arm

Hand

Hand

Trunk

Hip/thigh/leg

As soon as an object is thrown it becomes a projectile.

The distance an object travels is dependant on many factors, including: Speed of release Angle of release Height of release

A projectiles speed of release is determined by: Force summation Levers

The greater the speed of release = the greater distance traveled.

When aiming for maximum distance, the optimal angle of release is 45 degrees

Different activities require a different angle of release…

e.g. Hand ball shot at goal (-45 degrees)

e.g. Throwing a shot put (45 degrees) – High release to get greater distance

By increasing the height of release, the object will travel a greater distance

e.g.

Complete the revision worksheet